Normal WDM (sometimes called BWDM) uses the two normal wavelengths 1310 and 1550 nm on one fiber. Coarse WDM provides up to 16 channels across multiple transmission windows of silica fibers. Dense WDM (DWDM) uses the C-Band (1530 nm-1565 nm) transmission window but with denser channel spacing.OverviewIn, wavelength-division multiplexing (WDM) is a technology which a number of signals onto a single by using different (i.e., colors) of. A WDM system uses a at the to join the several signals together and a at the to split them apart. With the right type of fiber, it is possible to have a device that does both s.